✔️ Android
✔️ Web
✔️ Windows (Thanks to @alexmercerind)

Import it:

import 'package:system_theme/system_theme.dart';

Use the getter SystemTheme.accentInstance.accent to get the system accent color.

final accentColor = SystemTheme.accentInstance.accent;

To reload the accent colors, use the method load():

await SystemTheme.accentInstance.load();

You can load the colors on main, so the colors can't be wrong at runtime:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await SystemTheme.accentInstance.load();
  runApp(MyApp());
}

Use the getter SystemTheme.darkMode to check if the device is in dark mode.

final darkMode = await SystemTheme.darkMode;

Feel free to open an issue if you find an error or make pull requests.